The Worlds Between
by blodeuweddbach
Summary: When Loki falls from the Bifrost, he ends up in a world he never knew existed. Trapped in the Otherworld, he seeks a way to Earth to take his revenge and the throne that he was born for. But he may need the help of a princess to do it. A fic about what happens MCU's depiction of Norse mythology meets a retelling of Welsh folklore. Post-Thor film. Loki/OC.


**Prologue**

The Nine Realms of Yggdrasil floated before the Allfather, the images of the known worlds suspended in mid-air. Beside him, the two young princes stood transfixed, watching the galaxies swirl past them.

Normally, the lessons the boys received were tedious, lectures about the various allies of Asgard and the great history of the realm. Thor and Loki did not often study together. The elder brother preferred the training yard even at so tender an age, and the younger received tutelage in magic from Frigga. A certain level of political understanding was expected from members of the royal family, however, and a tutor on such important matters was called in to teach both princes together, for when they ruled in their own rights.

Today was an exception; a lesson taught by the King himself.

"As Allfather," Odin explained, one hand on each of his sons' shoulders, "I have a responsibility to keep the peace between the realms. It is my most important task, and one that is not easy to complete."

"If anyone should challenge _me_ as king," Thor interjected, a smug expression playing on his young features, "I should defeat them easily with my army. Is that how _you_ keep the peace, Father?"

Odin smiled down at his eldest son. "The intervention of Asgard's forces is sometimes necessary, yes. But a good king does not look to violence to rule his people. It is better to look for peaceful means, to negotiate with others and reach an agreement if you can. This is what we call _diplomacy_ , Thor, and as a weapon it will serve a king as well as any sword or army."

Thor looked dubious, but said nothing to contradict the Allfather. On the King's other side, Loki had been ignoring the conversation between his brother and father entirely, and was instead looking closely at the map, his narrow face contorted in concentration.

"Asgard," he recited, pointing to each realm in turn. "Vanaheim. Nidavellir. Jotunheim. Muspelheim. Alfheim. Svartalfheim. Hel… Midgard."

The boy hesitated, his blue-green eyes drawn to the image of the planet slowly rotating before him, swathes of land surrounded by vast oceans.

"Well remembered, Loki," Odin praised, nodding his head. "But what is it that troubles you?"

Loki pointed to Earth. "What are those lights, Father, dotted around Midgard? I have never seen them before."

The King's lone eye searched the map. Sure enough, dozens of miniscule golden lights were dispersed over the entire realm. The King's face became serious, as it always did when he spoke of difficult matters, and he cleared his throat.

"Those," he explained, earning the attention of both princes, "are portals."

"Portals?" Thor repeated, his eyes wide. "Why are there so many of them?"

Odin's gaze remained firmly on the map, deep in thought.

"Those portals lead to other worllds. Some of them are worlds we know of, the Nine Realms." He waved a hand to some of the other realms; a few golden lights glowed nearby, but nowhere near the number that surrounded Midgard. "Others are a mystery, even to Heimdall."

Loki blinked in surprise, grasping Odin's meaning much more swiftly than his brother. "So we don't know where they go?"

Odin shook his head. "No. The mortals sometimes wander into them unknowingly, as is the case here-" he pointed to an area of ocean upon the planet's surface, where a golden light glowed brightly, "in what is known as the Bermuda Triangle."

Never before had both boys stood so quietly during their lessons, and Odin took this as a chance to continue.

"Others, the scholars believe, lead to worlds similar to ours- home to beings as powerful as you or I. There is one here, at the summit of a mountain the mortals call Mount Olympus. No Asgardian has ever passed through it."

The King's voice had gradually faded away, and he stood, eye narrowed at the small dots of light. He then seemed to regain his train of thought, however, and he looked down at Thor and Loki.

"I think that concludes your lessons for today." With a clap of Odin's hands, the map vanished, leaving both princes blinking at empty air. "You may go."

Thor needed no further invitation, skidding out of the room as fast as his legs would carry him. Loki, meanwhile, lingered a little longer, pausing before the door to think about what his father had said.

There were worlds that no one, not even the Asgardians, knew of. That not even Heimdall could see. _How can such a thing be?_ Loki wondered to himself, puzzlement creasing his brow. But as he left the room, the young boy promised himself, in the quiet of his heart, that he would be the first to see them.

Then, perhaps, he could finally leave his brother's shadow.

* * *

 **Centuries Later**

" _I could have done it Father_!" Loki's voice had begun to crack in his desperation. " _I could have done it! For you! For all of us!_ "

His fingers gripped the edge of the Bifrost, its glory shattered at the hands of the thunder god. Above him, Odin turned his saddened gaze toward his adopted son.

" _No, Loki._ "

Those two words were all Loki needed to hear. His pale fingers relinquished their grip, one by one. Somewhere on the bridge, Thor cried out.

" _Loki, no…NO!_ "

Too late.

He let go. Let go of everything; his betrayal, his desperation, his hunger for power. He let it all fall away as he himself fell, down into an abyss, the roaring in is ears drowning out his brother's anguished shouts and the dark swallowing up the sight of Odin's face staring down at him.

In the void, there was no time. It was the torturous passage of years, and the terrifying fleeing of moments. Loki watched chaos erupt around him, worlds he never could have imagined consumed and destroyed, and he shut his eyes, wanting to erase it all, wanting it to _stop_ …

One resounding image flashed before his vision throughout the descent. Odin, staring down from the Bifrost, watching him fall without a word on his lips. Hatred coursed through his veins then; how he would pay. How they would _all_ pay.

He was angry now, falling through this exploding chaos. Not even the Silvertongue could talk his way out of this fate.

But the one thing Loki had not counted on was something that appeared suddenly beneath him, pulling him irresistibly into its golden-tinged embrace.

 _Daylight._

* * *

 **Part One: Of Canines and Crash-Landings**

The hounds were baying in the undergrowth ahead, the scent of blood driving them onward. Ari did her best to follow the sound, coaxing her mare along the narrow hunting trails. The horse was beautiful, white as a newly-fallen snow, a gift from her mother. She was also skittish. She nickered and pulled at the reins at every small noise, and it was all Ari could do to keep her calm and moving.

"Just a little bit further," she coaxed the mare, reaching out to pat her neck. The dogs began to bark and howl even more loudly than before, and the horse snorted her surprise, tossing her head. Ari grit her teeth. _Sounds like they've caught something._

The annual royal hunt was a tradition that Ari had never particularly looked forward to. She didn't like the idea of watching her father's hounds bring down some poor creature or another, but she understood its significance. It heralded in the beginning of autumn, a season of plenty and preparation for a harsh winter to come.

It was her first hunt since coming of age, the only year since then that the stocks of the royal woodlands had been deemed large enough for the season's sport. The King and Queen, along with their most favoured courtiers and closest friends, had ventured out early that morning, and she had been obliged to go with them. She was Crown Princess of Annwn, after all, and there were traditions she must uphold.

For all of her faults (and, according to her mother's constant lecturing, she had _many_ ), Ari had always been a good horsewoman. Not excellent- she had never had the patience to learn all that the riding instructor wished to teach her- but good enough to have outpaced the rest of the hunting party. She was closest to the hounds, could hear the others riding some way behind, and would be the first to come across whatever grisly spectacle the dogs had begun.

Her father had aimed at an unsuspecting doe some time ago, and he had been convinced that his arrow had hit its mark. The hounds had given chase, and _they_ had followed. Ari had to admire the doe's tenacity; it had lasted much longer than she would have expected, wounded as it supposedly was. The sounds the dogs were making left her in no doubt that it would all be over for it soon, however.

Ahead, the chaotic tangle of trees either side of the trail opened up into a small clearing. Ari pulled at her reins a little, slowing her mare to a trot as she approached.

The hounds had grouped around their quarry, pushing it back against a vast gnarled oak where it could not escape them. Amid the flurry of tails and paws, and the shadow of the tree's vast boughs, it was difficult to see what exactly they had cornered.

Then her eyes adjusted to the gloom, and Ari gasped.

It was not a deer the dogs had surrounded, but a man. He had his back against the tree, one hand holding onto it as though to keep him upright, the other raised as though to strike the dogs if they attacked. But they weren't attacking. Ari could see, now, that despite the din that they were making, the hounds had made no move to harm the stranger.

The man noticed her then, pale eyes finding hers in the gloom, and for a moment her mind went completely blank.

"Call them off," the stranger called to her, in a hoarse voice. Ari snapped to her senses then, releasing the reins to clap her hands together.

"Back!" She called to the dogs, who turned back to look at her. They were loyal beasts, her father's other pride and joy, and she had known them since they had been puppies. They obeyed her instantly, running towards her mare with lolling tongues and wagging tails. Proud of themselves. Ari ignored them for the moment, however, glancing back to the man beside the oak tree.

"Are you hurt?" She asked him. He seemed weakened, unable to push himself away from the trunk of the oak, his shoulders sagging slightly. He was cloaked in shadow, so Ari could not make much of his features, except that he looked to be lean and tall.

"No," the man answered finally, the word almost breathless. "I am… a little weak."

He sounded it, and Ari slid from her saddle onto the ground to walk toward him. Some of the more confident hounds followed at her ankles.

"What are you doing in these woods?" Ari asked the stranger as she approached him. Her mind cautioned her against such an action, but she reasoned that the remainder of her party were not far behind, and she had two dozen hunting hounds at her call. "These are the King's hunting grounds. It's forbidden for the public to walk through them on the day of the royal hunt."

These were well-known rules on Annwn; it protected both the game from any other hunting parties, and civilians from accidentally getting hit with arrows.

"And which King would that be?" The stranger asked, his breathing laboured. Ari stopped for a moment, looking at him. _He is either a madman, or a terrible comedian._

She still couldn't see much of his face, save that it was pale, so she didn't know whether he was jesting with her or not. She decided to take his comment at face-value; that he genuinely did not know who his monarch was. _Perhaps he has hit his head._

"King Arawn of Annwn, of course," Ari answered. "Ruler of the Otherworld. _My father_ ," she added for good measure. Just in case this stranger had considered trying to harm her, it would do well to let him know that she had armoured guards just a scream away.

"I see." That was the man's only answer. He slumped back against the tree, panting for breath. Her incredulity at his ignorance forgotten, Ari rushed forward, lacing his arm over her shoulders to help him stand. The man was at least a head taller than her, and she could see now that his hair was dark and dishevelled. She could only see his face in side-profile, but it was high-boned and handsome, as though carved from marble. For a moment, she could only stare at him.

"Ari!"

Her mother's voice called from across the clearing, and both Ari and the stranger looked up to see the remainder of the hunting party assembled there. The Queen was looking at them with wide eyes, shocked, but the King's were narrowed in suspicion.

"Who is that?" Arawn asked, nodding towards the stranger. When he made no move to introduce himself, Ari spoke instead.

"The dogs found him," she explained to her parents. She was sure there would be plenty of time for introductions later. "He is unwell."

The King's dubious expression never wavered, though he could not ignore the weight of everyone's eyes on him. He sighed.

"Then he shall be taken back to the palace," Arawn conceded sternly, "where he may find rest."

The stranger nodded weakly at that. Ari thought better than to be so easily cowed by her father's words. The King hadn't finished, and she knew it.

"Once you are well enough, you will provide us with a reason as to why you are in these woods on the day of the royal hunt." The King's eyes narrowed even further as he spoke. "And you might tell us where exactly you are from, for _you_ are no child of Annwn."

* * *

Falling through the void had robbed him of his energy, and it was all Loki could do to stay upright in the saddle as the retinue moved out of the woods. They always brought a spare horse, one of the men had told him, as the creatures had been known to hurt a leg in the twisted roots and thick undergrowth of the forest. Loki was silently grateful for that foresight as the canopy gave way into open fields.

Above them, perched atop a high hill, rose a palace. Two huge curtain walls ran around it, while the fortress itself rivalled that of Asgard in its size and splendour. Flags flew from its many turrets, and walkways between the towers were suspended hundreds of feet above the ground. Spiral staircases twisted around them like sleeping serpents. It seemed nearly impossible that it had managed to remain hidden from view for so long.

Months ago, Loki might have been impressed by such a sight. Now, when he looked upon the palace of the strange world he found himself in, this _Annwn,_ he felt nothing at all.

The fear and anger he had felt in the void, however, had not left him. He could still feel them under his skin like poison, filling his mind with pain. If he closed his eyes, he could still see those dying galaxies, could still feel the empty cold of oblivion. It took all he had to keep himself from slipping sideways from his horse.

There was so much torment racing through his mind that he couldn't find it within him to feel much about his current situation at all. No grief, no gratitude; it was less than nothing that he had found his way there. The only thing he could think of was how he would go about getting revenge.

"We're almost there now," a voice on his right told him. Loki looked up to see the young woman, the one they kept calling Ari, giving him a small smile. He felt like laughing in her face. _You would not smile, foolish girl, if you knew what I'd seen_. _If you knew what I plan to do._ If he could not have Asgard, he would take the next best thing, no matter the cost.

He would rule Earth, and not even Thor would stop him this time.

Still, he managed to nod at Ari, watching her even as she looked away again. Her hair was a shade of reddish-brown, tied into a long braid down her back. She carried herself with the easy grace of someone who had never wanted for anything in her life. Her mouth turned up in a natural smile, her cheeks were freckled, and her eyes bright. _And what eyes they are_. They were peculiar, the irises a bright silver.

The others, too, all seemed to have odd coloured eyes. Purples, pinks, sapphire blues and emerald greens, oranges and reds and golds. It only served as a reminder to how far from Asgard, from all he had ever known, he now was.

The King of this realm appeared to be no fool, however- _he_ also knew that Loki was far from home. He was acutely aware of the man's piercing stare even though he rode in front of him. He had demanded that Loki tell them, eventually, where he had come from, but seemed content for now to merely speculate on that point. _Good_. That gave Loki more time to decide on his story.

Loki could remember almost all of the lessons he had been given on the Nine Realms. He had never heard of a place named Annwn, nor of the people who inhabited it. He was completely in the dark, and it irked him beyond words to know nothing of where he was nor how he was going to get out.

His arrival had been sudden. One moment, he had been falling through the void; the next, he had been falling through the trees onto solid ground. Whatever doorway had given him entry to this world had closed again the moment he had passed through it, for when he had gotten to his feet, wheezing and weak, the sky was an empty blue.

Then the dogs had come. _They_ were strange as well, white as snow save for the blood-red fur of their ears. Loki had never been fond of dogs, and he doubted his mind would be much changed after today.

The retinue finally stopped, after climbing the vast hill and passing through the two gatehouses of the castle walls, in what appeared to be the front courtyard of the palace. Loki unsteadily got down from his horse, having to grip the saddle until his knuckles whitened to keep from falling.

"Iwan," the King addressed the man who had walked down the front steps of the palace to greet them, "have one of the guest chambers in the east wing prepared. We shall be having a visitor for a few days." Here he shot another glance toward Loki, who simply stared back. He would not be intimidated by anyone, least of all the King of some unknown backwater.

Iwan bowed at the waist, daring to glance briefly at the 'visitor', before hurrying back indoors. Then the King turned to him.

"The guards will show you to your chambers. You are free to rest for the evening, but I wish to speak with you at your earliest convenience in the morning."

'At your earliest convenience' was uttered so darkly that Loki had no doubt it would be at the King's, rather than his own, convenience entirely. But he was not fool enough to contest it, and he merely offered a weak smile.

"Thank you for your hospitality," he said, mimicking Iwan's bow. The rest of the hunting party seemed to be placated a little by his display, but not the King. His eyes, golden as a hawk's, regarded him warily. He merely nodded, before turning towards the door.

"Come, Delyth, Ari," he called behind him as he went. Ari, and a woman who could only have been her mother, for she shared that same reddish-brown hair, followed him up the steps, disappearing into the depths of the palace. Ari, however, had glanced back at him before she had vanished. There was something more than curiosity in that gaze, and even in his exhausted, raging mind, Loki made a note of it.

It might just prove useful to his cause.

* * *

"How did you know he wasn't from Annwn?" Ari asked her father once dinner was over. They sat opposite each other in armchairs beside a roaring fire. One of the hound's puppies lay at her feet, dozing. It took a few moments for Arawn to answer her, his eyes fixed on the flames in the grate.

"His clothes, for one," the King said, meeting her gaze for a moment. "Didn't you notice anything about them?"

Ari felt her cheeks warm a little. She hadn't even thought to look at his clothes. She had never been particularly observant, a trait Arawn was renowned for throughout his kingdom. When she gave no answer, her father continued.

"They were strange. Metal I had never seen before, clothes cut in a fashion unknown to us. Arbitrary things, perhaps, but if you are to be Queen one day you must get used to reading people well, Arianwen."

She sighed a little at the use of her full name, but took his point. As well as being unobservant, she had often been overly trusting, something she could not afford to be when the responsibility of the throne was eventually placed upon her.

"Then there were his eyes," the King continued. "The colour was dull compared to our own, if you saw them." The fact that he doubted she noticed anything at all was implied heavily, and Ari could feel herself getting frustrated. She _had_ seen his eyes; if anything, she had seen too much of them. Their colour was soft and uncertain, not the piercing gaze she was so used to. It had captivated her attention even as it distracted her wits.

"And the third point?" Ari asked. Unobservant as she may have been, she always knew when her father was not yet done with his lectures. He gave her a small smile.

"The third point was less about observation and more about intuition," Arawn explained, focusing his eyes back on the fire. "Your mother often complains that I don't share her intuition when it comes to parenting matters, which is likely true, but when it comes to matters of _hudau_ I can always tell."

 _Hudau_. Enchantments. "You're saying this man knows sorcery?"

Arawn nodded. "I have studied _hudau_ since I was a boy. You'll excuse me from self-flattery if I said that I am an adept sorcerer myself."

Ari knew that to be true more than anyone. Her father's skills had always lain in the arcane arts; its study was a requirement of any heir to the throne of Annwn. She had inherited some of his skill herself. "You're more than 'adept', Father."

He smiled at that. "I thank you, my dear. As such, I have my own ways of knowing if someone is a sorcerer, a wielder of spells. Call it intuition, call it sensing, but I _know_. And I know that the man currently staying in the east wing is an adept enchanter himself, though he would hide that from us."

Ari didn't know whether to believe her father's judgement on that matter. He was a naturally suspicious man, and trust came with difficulty for him. It wouldn't be the first time he had doubted the character of an innocent man.

"Why would he try to hide it, though?" she asked him. "If he is a sorcerer, he might have prevented himself being taken to the palace, or at least hidden himself from us in the forest." _Or even try to overpower us entirely_. She left that part unsaid, however, remembering how easily she had overlooked such a danger. _You're a fool sometimes, Ari_.

"That is what I hope to learn tomorrow," Arawn answered vaguely. "As well as how he got here."

"I've been thinking about that as well," Ari admitted. A hint of worry twisted in her stomach. To ignore it, she reached down and lifted the sleeping puppy into her lap, rubbing her thumb gently over one ear. "I remember you telling me that portals used to open and close of their own accord on Annwn, before grandfather closed them for good."

Arawn sighed heavily at that. "I was pondering the same. It would appear that this man, whatever world he's from, got here through a portal of some kind. It may have been made by him, or it may have opened spontaneously. Such a thing has never happened in my lifetime, but my father told me stories of things from other worlds finding their way to Annwn through these self-generating portals. Strange things, beautiful things, some _terrible_ things." He shook his head determinedly at the fireplace. "I fear we are headed back to those days, Ari. I do not know how I will protect our people from threats we have never seen and cannot predict."

Ari reached over to place her hand on her father's. "You may not have to. There may be some other explanation entirely."

Arawn nodded at that, turning his palm to take her hand in his. She remembered walking through the gardens as a child, hand in hand with her father, feeling as though nothing could harm her as long as he were near.

"I hope you are right, child. Perhaps we need not trouble ourselves with threats from other worlds."

There was something in his tone gave her pause. "And do you think _this man_ is a threat?"

King Arawn laughed softly. "As to that, my dear, only time will tell."


End file.
